|Publication number||US7021796 B2|
|Application number||US 10/340,977|
|Publication date||Apr 4, 2006|
|Filing date||Jan 13, 2003|
|Priority date||Jan 13, 2003|
|Also published as||US20040136081|
|Publication number||10340977, 340977, US 7021796 B2, US 7021796B2, US-B2-7021796, US7021796 B2, US7021796B2|
|Inventors||James Kevan Guy|
|Original Assignee||The Boeing Company|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (12), Referenced by (1), Classifications (7), Legal Events (5)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The present invention relates to optical systems, and more particularly to a light engine able to focus light from a light source into a light beam having a reduced spot size and increased optical energy.
Light engines (often referred to as “illuminators”) are used in many applications, and especially in fiber optic illumination applications. Light engines are typically used to locate a source of light remotely from an area to be illuminated. Several advantages are provided by being able to locate the light engine remotely from the area where the light it produces is to be used. Safety, spectrum control, thermal concerns, etc., are but a few reasons why it is often desirable to locate the light engine remotely from an area or object that is to be illuminated.
The problem with using light engines in fiber optic illumination systems is the needed efficiency. Direct illumination by a light source is the more efficient means for providing light. For fiber fed illuminators to compete with direct illumination systems, the efficiency and the amount of light transported by a fiber (or optical fiber bundle) needs to approach the system efficiency of a direct illumination system.
A specific limitation with present day fiber fed illuminators is the criticality of the diameter of the spot size of the beam of light produced by the illuminator. Ideally, the spot size should be minimized so as to better concentrate and focus the optical energy of the beam into the input face of an optical fiber or optical fiber bundle. There have been many attempts, with limited success, to control the spot size in an effort to reduce it so that the light beam from an illuminator can be focused into a smaller diameter optical fiber or a smaller diameter optical fiber bundle.
Many present day fiber fed illuminators incorporate some form of reflector system which is used to more closely focus the light from a light source of the illuminator. Such a system is shown in
Many present day approaches which attempt to reduce the spot size of the light beam from a fiber fed illuminator make use of either a standard ellipsoidal reflector, a dual ellipsoidal reflector, a parabaloid reflector with some form of optical lens, and various other facetized versions of these approaches. All of these approaches are subject to a common geometric limitation. That limitation is that while a typical ellipsoidal reflector may very accurately direct the light source to an output location (i.e., focus) at source points close to the median of the ellipse, the reflected light diverges away from the output location as the source point moves away from the median of the ellipse. The spot size is governed by the numerical aperture (NA) of the accepting target, the solid angle of the source radiation pattern and the source's physical size.
In view of the above, it will be appreciated then that a standard ellipsoidal reflector has a geometric limitation for the spot size that it can produce. There have been many attempts to “piece wise” control the distribution of the output by facetizing the reflector. Facetized reflectors are designed to “tweak” the distribution of light at the target by orienting areas on the reflector surface (facets) in order to meet some predetermined output beam pattern. However, facetized reflectors still may not actually focus the source light better, but can sometimes distribute the light to better meet some predetermined requirement. More precise control of the output of the light source would allow even more light to be focused into a smaller diameter spot. In practical terms, this would allow for a smaller diameter optical fiber or optical fiber bundle to be used to receive the optical signal from the signal source to handle a given illumination task.
Accordingly, there still exists a need for a fiber fed light engine which is able to more closely focus a light beam from a light source in a manner that reduces the spot size of the beam to a greater degree than what is possible with present day light engines. Reducing the spot size of the beam would allow smaller diameter optical fibers and optical fiber bundles to be employed, which would significantly improve the overall efficiently of the system, in addition to reducing the overall cost and weight of a fiber optic illumination system.
The present invention is directed to a light engine which is capable of producing a beam having a reduced diameter spot size, and is thereby able to be used with smaller diameter optical fibers and optical fiber bundles or other light transmitting apparatuses. The light engine of the present invention, in one preferred form, includes a housing having a central hollowed out portion within which a light source is disposed. The light source generates an optical input signal. The hollowed out portion opens into a plurality of reflector portions that form apertures in the housing. The reflectors, in one preferred form, are arranged at 90° angles to one another. A refractive optical element is disposed adjacent to the light source in each reflector to receive a first portion of the optical input signal and to produce a first optical output component which is directed through an associated one of the apertures at a target. Each reflector is disposed adjacent the light source and coaxially aligned with an associated one of the refractive optical elements so as to reflect a second portion of the optical input signal and produce a second optical output component that is associated with one of the first optical output components and each focused at an associated target. The second portions represent only “high angle”, accurate light ray components of the light generated by the light source. The first and second optical components cooperatively produce beams that have substantially similar spot sizes and which overlap one an other at the target. The resulting spot is not only smaller in diameter than what is produced by a conventional reflector system, but is also significantly increased in intensity.
In one preferred form the light engine comprises a housing having four ellipsoidal reflectors arranged at 90° angles relative to each other, with the light source disposed at a common focus of the reflectors. The optical element, in various preferred embodiments, comprises a refractive optical element, and more specifically a condensing lens, a light pipe or a gradient index (GRIN) lens. The refractive optical elements are disposed within the reflectors and effectively create a “shadow” zone within each reflector that extends from a central optical axis of each reflector up to an outer most edge of each reflector. The refractive optical elements effectively serve to capture the first portions of the optical input signal propagating within each reflector and to focus these portions into beams having a predetermined spot size that matches the spot size of the reflector. Second portions of the optical signal, which do not impinge the refractive optical elements, are focused (i.e., reflected) by the reflectors into beams each having a spot size substantially the same as that produced by the reflector's associated optical element, and further such that this beam overlaps the beam created by its associated optical element. The result is a significantly greater percentage of the optical input signal that is focused into a smaller diameter, higher intensity beam.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the invention.
The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
With further reference to
The reflector portion 20 b preferably includes a reflective surface 24 for maximizing the amount of light that is reflected from the reflector 20 b. The condenser lens 22 b is arranged forwardly in the direction of light propagation of the light source 18 in such a manner that a shadow zone 26 is created. Importantly, the shadow zone 26 is formed such that it extends to an outer most edge 28 of the reflector 20 b. The light source 18 is disposed at a focus 30 of the reflector 20 b. The reflector 20 b serves to reflect the accurate, “high angle” light rays 32 emanating from the light source 18. The condensing lens 22 b, however, operates to focus a forwardly projected portion of the light rays 36 onto the target plane 34. It will be noted that light rays 32 and 36 substantially overlap one another when they reach the target plane 34. In practice, the target plane 34 may be any form of optical coupling element which can be used to direct the optical energy received onto a face of a light transmitting element such as an optical fiber or optical fiber bundle. Since no optical energy is reflected rearwardly (i.e., to the left) in the drawing of
The light engine 10 of the present invention thus provides a means to significantly increase the optical energy transmitted to a face of an optical fiber bundle, or any other form of optical transmitting component, while concurrently reducing the spot sizes of the light beams produced by the light engine 10. The light engine 10 thus more efficiently transmits optical energy from a light source into an optical fiber bundle or other optical component for even more effective use in applications where optical fibers, light guides or other optical components are used to transmit light to a working device or element located remotely from the light engine.
The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US2803756 *||Jan 4, 1952||Aug 20, 1957||Mandrel Industries||Viewing chamber for gravity sorter|
|US4811174 *||Dec 2, 1986||Mar 7, 1989||Karl Zizala Metallwarenfabrik||Vehicle lighting device|
|US5235470 *||Aug 5, 1991||Aug 10, 1993||Cheng Dah Y||Orthogonal parabolic reflector systems|
|US5390265 *||Dec 17, 1993||Feb 14, 1995||General Motors Corporation||Fiber optic light coupler|
|US5924792 *||Feb 21, 1997||Jul 20, 1999||General Electric Company||Modular dual port central lighting system|
|US5967647 *||Jan 22, 1998||Oct 19, 1999||Robert Bosch Gmbh||Headlight for a vehicle, especially a motor vehicle|
|US6304693 *||Dec 2, 1999||Oct 16, 2001||Fiberstars Incorporated||Efficient arrangement for coupling light between light source and light guide|
|US6351058 *||Jul 12, 1999||Feb 26, 2002||Eg&G Ilc Technology, Inc.||Xenon ceramic lamp with integrated compound reflectors|
|US6406171 *||Jan 18, 2000||Jun 18, 2002||Koito Manufacturing Co., Ltd.||Vehicle indicator lamp|
|US6536921 *||Mar 7, 2000||Mar 25, 2003||Jerome H. Simon||Architectural lighting distributed from contained radially collimated light and compact efficient luminaires|
|US6554456 *||May 5, 2000||Apr 29, 2003||Advanced Lighting Technologies, Inc.||Efficient directional lighting system|
|US6635012 *||Mar 29, 2002||Oct 21, 2003||Fuji Photo Optical Co., Ltd.||Electronic endoscope apparatus provided with AC lighting light source|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US20050237623 *||Feb 22, 2005||Oct 27, 2005||Damian Fiolka||Optical unit for an illumination system of a microlithographic projection exposure apparatus|
|U.S. Classification||362/308, 362/328, 362/310|
|International Classification||F21V7/08, F21V8/00|
|Jan 13, 2003||AS||Assignment|
Owner name: BOEING COMPANY, THE, ILLINOIS
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:GUY, JAMES KEVAN;REEL/FRAME:013661/0672
Effective date: 20030107
|Oct 5, 2009||FPAY||Fee payment|
Year of fee payment: 4
|Nov 15, 2013||REMI||Maintenance fee reminder mailed|
|Apr 4, 2014||LAPS||Lapse for failure to pay maintenance fees|
|May 27, 2014||FP||Expired due to failure to pay maintenance fee|
Effective date: 20140404